Automatic level control (ALC) circuits are used in systems to reduce signal dynamic range. An automatic level control circuit can take a large input signal dynamic range and reduce it to a constant output power.
The function and construction of amplitude control systems, alternatively known as automatic level control circuits, are well known in the art.
In an automatic level control system, a power detector receives a coupled signal derived from an output signal. The detector generates a feedback signal that is applied to gain control circuitry within the automatic level control system. The gain control circuitry processes this feedback signal to provide an appropriate gain setting that is applied to the input signal such that the output signal is adjusted to an accurately designated power level. The desired output power level is generated even though the input signal applied to the automatic level control circuitry may have a variable amplitude level.
Generally, an automatic level control circuit should have a particular range of reaction time. In other words, there is typically an acceptable range of closed loop response, i.e. reacting too quickly is undesirable, yet reacting too slowly is also undesirable.
Current state of the art digital automatic level control architectures include closed loop response as a function of the input power operating point. This is undesirable because it forces a performance trade between the useable signal dynamic range and the acceptable range of reaction time.
The disadvantages associated with current ALC circuits have made it apparent that a new ALC circuit design is needed. The new design should be generally robust and should not force a performance trade between the useable signal dynamic range and the acceptable range of reaction time according to ALC parameters. The present invention is directed to these ends.